package com.maokeyang.stack;

import java.util.Stack;

/**
 * 20题
 */
public class Solution {

    public boolean isValid(String s) {

        Stack<Character> stack = new java.util.Stack<>();

        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);

            if (c == '(' || c == '[' || c == '{') {
                stack.push(c);
            } else {
                if (stack.isEmpty()) {
                    return false;
                }

                char topChar = stack.pop();
                if (c == ')' && topChar != '(') {
                    return false;
                }
                if (c == ']' && topChar != '[') {
                    return false;
                }
                if (c == '}' && topChar != '{') {
                    return false;
                }
            }

        }

        return stack.isEmpty();

    }

    public static void main(String[] args) {
        Solution solution = new Solution();
        String s = "[[]{]{}";
        System.out.println(solution.isValid(s));
    }
}
